Decay Dynamics of Excited Nd $^{+3}$ Ions in Nd:YVO $_{4}$ Following Weak Excitation

Decay dynamics of the upper-laser energy level of $hbox{Nd:YVO}_{4}$ are re-evaluated. In order to reduce the effects of re-absorption, comparative measurements among crushed samples with different doping concentrations were conducted. The magnitude of re-absorption was estimated experimentally by comparing the relative intensity of the emitted fluorescence spectra at different wavelengths, and estimated theoretically by employing a simplified model. The temporal decay dynamics are found to be non-exponential and the associated rate parameters are presented. The room temperature intrinsic life time value of the $^{4}hbox{F}_{3/2}$ energy level is found to be significantly shorter than the value accepted today.      

A 10 MS/s 11-bit 0.19 mm $^{2}$ Algorithmic ADC With Improved Clocking Scheme

A 10 MS/s 11-bit algorithmic ADC with an active area of 0.19$~{hbox{mm}}^{2}$ is presented. Using an improved clocking scheme, this design overcomes the speed limit of algorithmic ADCs. The proposed ADC employs amplifier sharing, DC offset cancellation, and input memory effect suppression, resulting in reduced area and power, and high linearity. The ADC implemented in a 0.13$~mu{hbox{m}}$ thick gate-oxide CMOS process achieves 69 dB SFDR, 58 dB SNR, and 56 dB SNDR, while consuming 3.5 mA from a 3 V supply.      

InP DHBT Process in Transferred-Substrate Technology With $f_{t}$ and $f_{max}$ Over 400 GHz

In this paper, a double heterojunction bipolar transistor (DHBT) process has been developed in transferred-substrate (TS) technology to optimize high-frequency performance. It provides an aligned lithographic access to frontside and backside of the device to eliminate dominant transistor parasitics. The transistors of $hbox{0.8} times hbox{5}hbox{-}muhbox{m}^{2}$ emitter mesa feature $f_{t} = hbox{410} hbox{GHz}$ and $f_{max} = hbox{480} hbox{GHz}$ at a $hbox{BV}_{rm ceo} = hbox{5.5} hbox{V}$. Parallel to the device setup, a multilevel metallization scheme is established. It serves as construction kit for 3-D configurations of active and passive elements. High yield of the TS DHBTs, consistent large-signal modeling, and accurate simulation of complex passive elements have been demonstrated and have proved the availability of the technology for advanced millimeter-wave circuit design.      

Writing of Apodized Phase-Shifted Long-Period Fiber Gratings With a Computer-Controlled CO $_{2}$ Laser

We apply a $hbox{CO}_{2}$ -laser writing method to the fabrication of sophisticated long-period fiber grating (LPFG) filters. The method allows the position of the writing beam to be computer-programmed to produce the required grating profile without using any mask. We demonstrate the flexibility and the controllability of the method with a number of apodized phase-shifted LPFGs written in a germanium–boron codoped fiber.      

Spectroscopy and Diode-Pumped Laser Experiments of LiLuF$_{bf 4}$:Tm$^{{bf 3}+}$ Crystals

In this work we report on the 2-${mbi mu}$m laser emission of LiLuF ${_{bf 4}}$ crystals doped with Thulium trivalent ions (Tm:LLF) at different doping density up to 16%. We will present our results regarding growth, absorption and emission spectroscopy, Judd–Ofelt analysis and room temperature diode pumping laser experiments as a function of the dopant density. The best result is 56% of slope efficiency, with a maximum output power of 280 mW. The emission wavelength ranges between 1985 and 2038 nm, exploiting the vibronic emission of Tm in LLF.      

Matrix Methods for the Dynamic Range Optimization of Continuous-Time $G_{m}$- $C$ Filters

This paper presents a synthesis procedure for the optimization of the dynamic range of continuous-time fully differential $G_{m}$-$C$ filters. Such procedure builds up on a general extended state-space system representation which provides simple matrix algebra mechanisms to evaluate the noise and distortion performances of filters, as well as, the effect of amplitude and impedance scaling operations. Using these methods, an analytical technique for the dynamic range optimization of weakly nonlinear $G_{m}$- $C$ filters under power dissipation constraints is presented. The procedure is first explained for general filter structures and then illustrated with a simple biquadratic section.      

An 8.6 mW 25 Mvertices/s 400-MFLOPS 800-MOPS 8.91 mm$^{2}$ Multimedia Stream Processor Core for Mobile Applications

For the demands of mobile multimedia applications, a stream processor core is designed with 8.91 ${hbox {mm}}^{2}$ area in 0.18$ mu{hbox {m}}$ CMOS technology at 50 MHz. Several techniques and architectures are proposed to achieve high performance with low power consumption. First of all, an optimized core pipeline is designed with 2-issue VLIW architecture to achieve the processing capability of 400 MFLOPS or 800 MOPS. In addition, adaptive multi-thread scheme can increase the performance by increasing hardware utilization, and the proposed configurable memory array architecture can reduce off-chip memory accessing frequency by caching both input data and output results. Furthermore, for graphics applications, a geometry-content-aware technique called early-rejection-after-transformation is proposed to remove redundant operations for invisible triangles. As for video applications, the proposed video accelerating instruction set can support motion estimation for video coding. Experimental results show that 86% power reduction and more than ten times speedup of the VLIW architecture can be achieved with the proposed techniques to provide the processing speed of 25 Mvertices/s and power consumption of 8.6 mW. Moreover, CIF (352 $times$ 288) 30 fps video encoding with the search range of {H[ $-$24,24), V[ $-$16,16]} is also supported by the proposed stream processor. By supporting both video and graphics functions, this highly efficient, high performance, and low power processor core is applicable to multimedia mobile devices.      

Temperature Effect on $Ku$-Band Current-Reused Common-Gate LNA in 0.13-$mu{hbox{m}}$ CMOS Technology

This paper presents the temperature effect on a Ku-band NMOS common-gate low-noise amplifier (CG-LNA). The temperature characteristics of an NMOS transistor and spiral inductors are obtained over the temperature range from 253 to 393 K. These results show that the optimal bias condition minimizes the transconductance and drain current temperature variations. Based on these results, a current-reused CG-LNA with good temperature performance is designed. At ambient temperatures, the CG-LNA has a measured power gain of 10.3 dB and a noise figure (NF) of 4.3 dB at 15.2 GHz, while consuming 4.5 mA from a 1.3-V power supply. When the temperature varies from 253 to 393 K, the CG-LNA has a power gain variation of 3 dB, NF variation of 2 dB , and dc power consumption variation of 11.9%. This paper is the first to report the temperature effect on Ku-band CG-LNAs.     

Nonpolar Nonvolatile Resistive Switching in Cu Doped $hbox{ZrO}_{2}$

In this letter, the unique reproducible nonpolar resistive switching behavior is reported in the Cu-doped ZrO₂ memory devices. The devices are with the sandwiched structure of Cu/ZrO₂:Cu/Pt. The switching between high resistance state (OFF-state) and low resistance state (ON-state) does not depend on the polarity of the applied voltage bias and can be achieved under both voltage sweeping and voltage pulse. The ratio between the high and low resistance is on the order of 10⁶. Set and Reset operation in voltage pulse mode can be as fast as 50 and 100 ns, respectively. No data loss is found upon continuous readout for more than 10⁴ s. Multilevel storage is considered feasible due to the dependence of ON-state resistance on Set compliance current. The switching mechanism is believed to be related with the formation and rupture of conducting filamentary paths.     

Analysis and Design of the 0.13- $muhbox{m}$ CMOS Shunt–Series Series–Shunt Dual-Feedback Amplifier

This paper demonstrates the design methodology of the shunt–series series–shunt dual-feedback Meyer wideband amplifier. The small-signal S-parameters are obtained for the first time using the pole-and-zero analysis, thus giving the RF designers a detailed insight into the Meyer amplifier. A 10-GHz wideband amplifier is demonstrated in this paper, using 0.13-${rm mu}hbox{m}$ CMOS technology to verify our design theory. The experimental results of the S-parameters highly agree with our theory.      

A Novel 4.5$hbox{F}^{2}$ Capacitorless Semiconductor Memory Device

This letter proposes a novel 4.5$hbox{F}^{2}$ capacitorless dynamic random access memory cell with a floating gate (FG) connected to drain via a gated p-n junction diode. The FG in the proposed memory device is for charge storage and can electrically be charged or discharged by current flowing through a gated p-n junction diode.      

Coaxial-to-Waveguide Matching With $varepsilon$-Near-Zero Ultranarrow Channels and Bends

We propose the use of metamaterial-inspired ultranarrow channels at cutoff to realize an interesting matching between a coaxial antenna and a waveguide. The anomalous properties of a channel at cutoff, analogous to those of zero permittivity materials, allow a simple matching design, valid for arbitrary waveguides, with large degrees of freedom in terms of geometry, length and possible bending of the connecting channel. Moreover, the static-like properties of the channel allow such matching, independent of the relative position of the antenna and possible bending and abruptions along the channel.      

Comments on “T–S Fuzzy-Model-Based Robust $H_{infty }$ Design for Networked Control Systems With Uncertainties”

This letter addresses that the linear matrix inequality condition relaxation for stability of the Takagi–Sugeno fuzzy networked control system is incorrect.      

Fast Passivity Enforcement of $S$-Parameter Macromodels by Pole Perturbation

This paper presents a fast iterative algorithm for passivity enforcement of large nonpassive macromodels that share a common set of poles. It is ensured that the maximum passivity violation is monotonically decreasing in each iteration step, and convergence to a passive macromodel is guaranteed.      

Fabrication and Characterization of Coplanar Waveguides on Silicon Using a Combination of SiO $_{2}$ and SRO $_{20}$

In this work, the use of silicon rich oxide (SRO) and chemical vapor deposition SiO$_{2}$ double layers as passivation films of coplanar waveguides (CPW) on high resistivity silicon (HR-Si) with an ${hbox{N}}^{+}$ backside is studied. The microwave performance of the fabricated CPWs is evaluated by computing the attenuation loss of the devices in the 0.045–50 GHz frequency range. Experimental results show that the ${hbox{N}}^{+}$ layer can be used without affecting CPW performance. Also, using a combined dielectric layer (SRO$_{20}$ /SiO$_{2}$ ), the attenuation losses are reduced compared to single dielectric layers.